Threat Level: High

Wasmannia auropunctata, commonly known as the Little Fire Ant, is a small pale colored ant that is widely regarded as the most dangerous threat to the Pacific Island region. This species has a monomorphic worker caste with 11-segmented antennae, two-segmented antennal club, antennal scrobes, short antennal scapes that do not surpass the posterior margin of the head, a gradually sloped mesosoma, and strong propodeal spines. Like all myrmicines, T. simillimum has two waist segments and a gaster armed with a stinger. See the video for additional field identification clues.

Tetramorium simillimum and T. caldarium are difficult to differentiate from W. auropunctata in the field (see also the video of T. simillimum. All are small, pale myrmicines with antennal scrobes and propodeal spines. However, these two Tetramorium species have 12-segmented antennae with three-segmented antennal clubs in addition to much smaller propodeal spines.

Wasmannia auropunctata is native to South America, but is rapidly spreading across many tropical regions, including the Pacific Islands. It is well documented as causing devastating damage to ecological and agricultural systems, and also poses significant human health risks. Wasmannia auropunctata is considered to be one of the 100 worst invasive species in the world by the IUCN/SSC Invasive Species Specialist Group (ISSG). See their web page for a more complete review of the biology, impacts and management.

If a specimen collected from an uninfected region is identified as W. auropunctata, it is recommended that the sample be sent to a taxonomic specialist for confirmation. If confirmed, it is recommended that an emergency eradication or management plan be initiated as quickly as possible.

Petiole with two waist segments (petiole & postpetiole)
Propodeal spines present & long
Antennal club with two segments Antennae 11-segmented
Antennal scrobe present & strong

	W. auropunctata	T. simillimum	T. caldarium	T. tonganum
Head
Profile
Total number of antennal segments	11	12	12	12
Antennal club segments	two	three	three	three
Propodeal spines	long	short	short	moderate
Hairs	long & sparse	short & sparse	short & sparse	long & abundant
Petiole node shape	square	square	square	rounded
	W. auropunctata	T. simillimum	T. caldarium	T. tonganum

• Antweb: specimen images, data & maps
  
  
• Global Invasive Species Database: information about ecology, distribution, impacts, management, references, links and contacts
  
  
• Bolton, B. (1995) A new general catalogue of the ants of the world. Harvard University Press, Cambridge, Massachusetts, 504 pp.
  
  
• Clark, D. B., C. Guayasamín, O. Pazmiño, C. Donoso, and Y. Páez de Villacís (1982) The tramp ant Wasmannia auropunctata: autecology and effects on ant diversity and distribution on Santa Cruz Island, Galapagos. Biotropica 14:196-207.
  
  
• De Souza, A. L. B., J. H. C. Delabie, and H. G. Fowler (1998) Wasmannia spp. (Hym. Formicidae) and insect damages to cocoa in Brazilian farms. Journal of Applied Entomology 122:339-341.
  
  
• Fabres, G., and W. L. Brown, Jr. (1978) The recent introduction of the pest ant Wasmannia auropunctata into New Caledonia. Journal of the Australian Entomological Society 17:139-142.
  
  
• Jourdan, H. (1997) Threats on Pacific islands: the spread of the tramp ant Wasmannia auropunctata (Hymenoptera: Formicidae). Pac. Cons. Biol. 3:61-64.
  
  
• Lubin, Y. D. (1984) Changes in the native fauna of the Galápagos Islands following invasion by the little red fire ant, Wasmannia auropunctata. Biological Journal of the Linnean Society 21:229-242.
  
  
• Ulloa Chacón, D., and D. Cherix (1990) The little fire ant Wasmannia auropunctata (Roger)(Hymenoptera: Formicidae). Pages 281-289 in R. K. Vander Meer, K. Jaffe, and A. Cedeno, editors. Applied myrmecology: a world perspective. Westview press, Boulder, CO. 741 p.
  
  
• Williams, D. F., (ed.) (1994) Exotic ants. Biology, impact, and control of introduced species. Westview Press, Boulder. [Numerous articles in this book concern the biology of Wasmannia auropunctata.]